Generally, surgical stapling has made substantial advances in the past decades. Specifically, in the area of internal anastomotic stapling the advances have been quite dramatic. Devices such as the Proximate.TM. ILS stapler, produced by the assignee of the present invention, Ethicon, Inc., Somerville, N.J., have enabled surgeons to perform operations and procedures which were heretofore perceived as difficult, if not impossible, with relative ease.
In performing surgical anastomotic stapling, generally the two pieces of lumen are attached by a ring of staples. During this procedure, a circular knife blade is used to separate tissue which is held within the circular ring. The circular ring is then removed with the stapler so that a circular opening withing the lumen is completed along the surgical stapling line.
In performing these surgical procedures however, it has become desirable to separate the anvil head on which the staples are clinched from the stapling portion from which the staples are expelled. Advances along these lines have been made in the past. It has been typical in the past that the stapling side of the mechanism is attached the head to the anvil portion through a "purse-stringed" gathering of tissue.
In addition, it has been found that when the tissue contained on the head portion of the stapler is attached to tissue contained on the anvil portion of the stapler, it is difficult to connect the anvil and head with proper alignment of the staples into the anvils contained on the anvil side.
Further, it has been found that it is difficult to perform such stapling within a circular stapler such that the head size is kept to a minimum on the outside with a maximum inner cavity, so that more tissue can be gathered within the anastomosed staple.
Also, although it may be desirable as part of this invention to have the tissue which is gathered, pierced by a relatively sharp trocar tip on the stapler head, it is not always desirable for the stapler head to be continually exposed with a sharp trocar tip. Rather, it has been found that it is more desirable feature is to have a sharp tip exposed only during a portion of the attachment procedure.